Much like [[UsefulNotes/JapaneseSiblingTerminology Japanese]], Chinese distinguishes between older and younger siblings. In Mandarin:
* 哥 ''Ge'': Older brother
* 弟 ''Di'': Younger brother
* 姐 ''Jie'': Older sister
* 妹 ''Mei'': Younger sister
In usage, these words are usually repeated twice; e.g., 妹妹 ''Mei mei'' for one's younger sister. It is generally considered impolite to call an elder sibling by name. In larger families, 大哥 ''Da Ge'' or 大姐 ''Da Jie'' would refer to the eldest male or female child and others would be numbered (二哥 ''Er Ge'', 三哥 ''San Ge,'' and so on). An elder brother is also sometimes referred to as 兄 ''Xiong,'' usually in the formula 兄弟 ''Xiongdi'' meaning "brothers" (in contrast to the Japanese 兄弟 ''Kyōdai'', which can either mean "brothers" or "siblings", including sisters). Many people mistakenly thought brothers and sisters as a whole would be almost obsolete, however one-child policy is obviously not meant to last very long (which otherwise will lead to eventual population decrease). For people born in 1980~2000s though, one-child family is dominant. Informally, it is not uncommon to call someone outside of your family by these names. Likewise, an elder sister can also be referred to as 姊 ''Zi'', as in the formula 姊妹 ''Zimei''(cognate with Japanese ''Shimai'') meaning "sisters". When the two are combined, the term 兄弟姊妹 ''Xiongdizimei'' means "siblings".
''Da Ge'' can also be used to address a non-related leader of an informal group, which happens overwhelmingly often in depictions of Chinese mafia bosses by Hong Kong films (the Cantonese ''Dai Lo'' is another term that gets thrown around quite frequently in these films). On that similar vein, ''Da Jie'' can be used to call said leader's wife, even if she is not, again, related by blood. This is comparable to the Japanese usage of 兄貴 ''Aniki,'' especially among (fictional) gangsters.
The youngest sibling older than you could be referred to as 小哥 ''Xiao Ge'' or 小姐 ''Xiao Jie,'' (小 ''Xiao'' = lit. "small") but that might not be as common as calling the youngest child 小弟 ''Xiao Di'' or 小妹 ''Xiao Mei.'' In any case, ''Xiao Jie'' is the Chinese equivalent of 'Miss' and used to address waitresses, retail clerks, etc. (And prostitutes, according to a few... interesting Chinese teachers. In fact, owing to this, ''Xiao Jie'' is an increasingly deprecated term in polite conversation, instead opting for the more appropriate 服務員 ''Fu Wu Yuan'' or "attendant") 妹妹 ''Mei Mei'', using the same two words but a different inflection, can also be used to refer to an attractive young girl; this is generally considered to be an impolite and inappropriate term, but used quite often (and deliberately) among Chinese male adolescents (and beyond).
Cousins are also referred to by these four terms with the addition of 堂 ''tang'' or 表 ''biao'' according to arcane rules having to do with whether/how your fathers are related (basically if the cousins are on your mother's side of the family or their mother is your father's sister, 表 ''biao'' is used, if their father is your father's brother, 堂 ''tang'' is used). Similarly, aunts and uncles are divided up by side of the family and maybe birth order relative to your parent. Contemporary people sometimes just don't bother the distinction of ''tang'' and ''biao''(nothing to do with one-child policy here), using ''biao'' for all cousins. Though in Chinese-speaking countries outside of China proper(such as Singapore and Taiwan), be prepared to address your cousins with those mouthfuls.
There are at least five ways to refer to your parents. Each set is "father" and "mother", written in Traditional, then Simplified Chinese in parentheses (if there is a difference):
* 爸爸 ''Baba'', 媽媽 (妈妈) ''Mama'', or just 爸 ''Ba'' and 媽 (妈) ''Ma'' - standard terms
* 阿爸 ''Aba'' and 阿媽 (阿妈) ''Ama'' - ''Ba'' and ''Ma'' above combined with the familiar term of address 阿 ''A''
* 老豆 ''Laodou'' and 老母 ''Laomu'' - a dialectal variation (e.g. it is used in Cantonese, pronounced ''Loudau'' and ''Loumou'')
* 爹 ''Die'' ("''d'yeh''", as opposed to the English word it resembles) and 娘 ''Niang'' - archaic terms, mostly heard in historical works
* 父親 (父亲) ''Fuqin'' and 母親 (母亲) ''Muqin'' (or collectively as 父母 ''Fumu'') - formal terms mostly used to refer to someone else's parents.
* 父王 ''Fuwang'' and 母后 ''Muhou'' - terms used by royal families
(In modern pinyin, the Q stands for a slightly-more-sibilant ''ch'' phoneme, so ''Fuqin'' is "foo-chin", as opposed to the ''[[ClusterFBomb other]]'' English word it resembles.)
Grandparents are again divided by which side of the family they belong to and there are again multiple sets of words. And grandchildren are also referred to differently depending on whether your son or daughter had them. And then once you get to aunts and uncles and great-aunts and great-uncles, depending on which side of the family they're from, or which side of which side of ''that'' family they're from, and whether they're older or younger than your direct relative in said family, you can pretty much stand by for YourHeadASplode.
Confused yet? All of this can also be modified by regional practice or family idiosyncracy. Just so you know. TheOtherWiki has much more comprehensive list of kinship terms [[http://en.wikipedia.org/wiki/Chinese_kinship#Common_extended_family_and_terminology here]].